Dental stool.



C. M. HEDMAN.

DENTAL STOOL.

APPLICATION FILED JULY 31, 1911.

,@423 Patented Nov. 19,1912.

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an inwardly extending shoulder 3.

cani. n. HEDMAN, or onIcAeo,

En STATES PATENT OFFICE.

ILLINOIS, ASSIGNOB, BY MESNE ASSIGNMENTS, T0

aan s. SMITH a son COMPANY, or PITTsBUneH, PENNSYLVANIA, A coPAnTNnP.-

. entr.

DENTAL strooit..

Specification of Letters Patent.

Patented Nev. 19, wie.

f Application filed July 31,1911. Serial No. 641,617.

1l o all rwhom it 'may concern Beit known that I, CARL -M. HEDMAN, a citizen of the United States, residing at- Chicago, in the county of Qook and State of illinois, have invented certain new and useful Improvements in Dent-al Stools, of which the following is a full, clear, concisel` and exactdescription, reference being had to the accompanying drawings, forming a part of this specification.

My invention relates to vertically adjustvable dental stoolsor the like, and has for its object the prov1sion in an article of this class of a simple and highly efficient method of raising the seat rod or post in the sup` portingvstandard, to efectually lock the .same 1n any desired position of vertical adjustment; also to provide means whereby Jche supporting standard may be moved slightly back and forth while the operator is at workwithout moving the base. e

The operation, construction and arrangement of the parts ofmy invention are fully described in the following specification, and' illustrated in the accompanying drawings, in which- Figure l is a side elevation of my iinproved stool shown partly in cross-section,.

and Fig. 2 isa detail viewvof the clutch mechanism for retaining the seat post at the desired height in the standard.

Referringto the drawings, 1 designates a stool base of any suitable material carrying a hollow head 2. Within the hollow head1 is T is shoulder is located a small distance beneath the upper end of the hollow head 2. Fitting tightly within the hollow head 2 and resting on the shoulder 3 is a helical spring 4.

This spring, which is'forced int-o the hollow head, should preferably he wound under initial tension. A ring 5 rests on the shoulder 3 inside of and fitting tightly against the helical spring. `This ring is driven `into this position and there spread, forcing the helical spring tightly against the wall of the hollow head 2. rlhe hollow heady 2 may be provided with internal threads to hold the spring 4 more rigidly in the hollow head; I have found in practice, however, that the method shown in the drawings is very lecient and that these threads are not absolutely necessary.

t3 designates a hollow standard enlarged at its lower l end and provided with a shoulder 7 to which is secured by threads or otherwise the helicalv spring 4. Driven or screwed into the standard 6 is a conical plug 8 which passes down through the spring 4 and the ring 5. This plug prevents the standard 6 'from taking a position too far from the vertical by abutting against the ring 5. and the shoulder 3.

Telescoping with the standard 6 is the seat post which is provided with teeth 10. These teeth, as shown in the drawings, are

square on their under surface and rounded on their upper surface. Resting upon the upper end of the plug 8 is the spiral spring 11. Upon this spring the seat postV 9 rests. When the seat post 9 is forced down into the standard 6 the spring 11 is compressed.

Mounted on the upper end of 'the standard 6 is the lever support 12. This support may either be cast on the standard or secured thereto in any one ofthe many ways known to those skilled in the art; A lever 13 is pivoted' to the lever support 12 by means of a pin or bolt in such a manner that the pin 14 will engage the teeth 10 of the seat post and so prevent the post from being moved while the lever is in its normal position. The pin 14 is preferably made of tool steel and is cast in the lever 13. A compression spring 15 fits into the cylindrical cavity 16 of the leversupport and also into the cylindrical cavity 17 of the lever holding the pin 14 in engagement with the teeth 10 of the seat post 9.- The spring 15 is strong enough to overcome any tendency of the spring ,11 to force the seat post 9 up in the standard when the lever is in its normal position.

Passing through the lever support 12 1s the threaded pin 18. This ypin projects into the longitudinal slot 19 of the seat post 9` and so prevents the rotation of the seat post in the standard and keeps the teeth 10'in engagement with the pin'14.

Near the top of the seat post 9 is a groove 20 encircling the same. On the top of the seat post is a small depression in which rests the anti-friction ball 2l. Mounted upon the seat post 9 is a cap which is secured to the seat post by means of the pin 22 which projects into the groove 20. Secured to the cap is the seat 23 which may be of any desired shape orstyle. The ball bearing 21 facilitates the seat being rotated on the seat post or rod 9 with very little friction.

Should the operator while sitting on the stcol desire to raise the same, he merely takes his weight oi of the seat and depresses the lever 13, disengaging the pin .14 with the teeth'lO of the seat post. The seat post is 1 compressingthe spring 11. y When the seat has fallen to tlie'desired height, the lever` is released.

All of the parts of my dental stool are of ver7 simple but durable construction. The seat may be raised or lowered by the operator seated on the stool-and he may-movel back and forth While seated thereonby son of the flexible spring 4. .A

I do not wish to be limited to the precise constructions and arrangements as illustrated, as c hanges can readily be made withoutrdepartlng from the scope of my invention. 'I claim as new and desire to secure ters Patent:

1. In combination, a base, a helical spring rigidly secured to said base, .a standard secured to said spring, a iseat carried by said by .Let-

standard, said standard having a conicalextension conformed to allow. lateral movement of the standard up to Va certain limit A in any direction, said conical extension being normallyl out of. engagement with the lbase but adapted to engage the base`to prevent lateral movement of the standard beyond a certain limit.

2'. -Incombmation a base, a helical spring rigidly secured to said base, a hollow standard secured to said spring, and a seat carried by said standard, said hollow standard having its lower end provided with a plug extending down through the spring, said plug being normally out of engagement with the base but being adapted to engage the base to prevent lateral movement of the standard beyond a certain limit.

3. In combinatlon a standard, a seat carried by the standard, ahelical spring secured to said standard, a base having a hollow head, an inwardly extending shoulder within said hollow head, said spring extending into'said hollow head and resting on said inwardly extending shoulder, and an expansionl ring resting on said shoulderand holdin said helical spring rigidly against the ins1de of said hollow head.

l. A stool or the like having a base, a hollow head carried by the base, an inwardly extending shoulder within said head, a helical spring fitting tightly within said hollow head and resting upon the inwardly extending shoulder, a ring forced down within Vsaid spring and forcing said spring against the walls of the hollow head, the upper end .of the spring being secured to a hollow standard which has its lower end provided with a conical plug extending downthrcugh the spring and adapted to engagewith the ring and the inwardly extending shoulder when `the hollow standard is moved to its extreme position substantially as described. In witness whereof, yI hereunto subscribe my name this 27th day of July, A. D. 1911'.

CARL M. HEDMAN. 

